KR100393512B1 - Method and apparatus for data transmission within a broad-band communication system - Google Patents

Abstract

During data transfer to the remote unit 113 using the fast supplemental data channel 105, all data has been communicated to the remote unit 113 or data transmission is interrupted by interruption during transmission. If all data is sent to the remote unit 113, the remote unit 113 drops the supplemental channel 105 before responding to the reception of the last frame transmitted, and the response uses the slow base channel 103. Perform. If an interruption occurs, if the remaining data to be transmitted is smaller than the predetermined size, data transmission continues using the base channel 103.

Description

TECHNICAL AND APPARATUS FOR DATA TRANSMISSION WITHIN A BROAD-BAND COMMUNICATION SYSTEM}

Communication systems are well known and consist of many types of elements, including land mobile radios, cellular radiotelephones, personal communication systems, and other types of communication systems. In a communication system, transmission is performed between a transmitting device and a receiving device through a communication resource (commonly called a communication channel). Until now, transmission has usually consisted of voice signals. Recently, however, it has been proposed to transmit other types of signals including high speed data signals. In order to facilitate operation, it is desirable to incorporate a data transmission function into the existing voice communication function, which uses the communication resources and other infrastructure of the voice communication system, while the data transmission operation is performed by the voice communication system. Because it is near.

One such communication system currently developed with transparent data transfer capability is the next generation Code-Division Multiple-Access (CDMA) cellular communication system, commonly referred to as cdma2000. Within this communication system all remote unit and base station transmissions occur simultaneously within the same frequency band. Therefore, the signal received at the base station or remote unit consists of a multiplicity of frequency and time overlapping coded signals from each individual remote unit or base station. Each of these signals are transmitted simultaneously at the same radio frequency (RF), but can only be distinguished by a particular encoding (channel). In other words, the signal received at the base station or remote unit receiver is a composite signal of each of the transmitted signals, and the individual signals can only be distinguished after decoding.

Remote unit data transmission within the cdma2000 communication system occurs by assigning a high speed data channel (called a supplemental channel) to the remote unit and transmitting data using the supplemental channel mentioned above. More specifically, if a data transmission is required, the remote unit is assigned a common traffic channel (fundamental channel) immediately, and the remote unit remains on the base channel until the supplemental channel is available. When the supplemental channel is available, data is sent using the supplemental channel. Once all the data has been sent, all the data has been sent and acknowledged, or after a certain time the supplemental channel is dropped and the remote unit continues to communicate over the base channel. If not all the data has been transmitted or only part of the data has to be transmitted (due to a reception error), the supplemental channel must be re-accessed and the remaining data must be transmitted.

Because the number of supplemental channels available in the communication system is limited, the ability to quickly re-access the supplemental channel is preferably limited to only a few remote units that compete for available supplemental channels. In other words, once the supplemental channel is dropped, subsequent data transfers or retransmissions on the supplemental channel may result in an appropriate reaccess process of the supplemental channel. The process may also take the form of maintaining a supplemental channel until an acknowledgment for the last data transmission is received. Therefore, a need exists for a method and apparatus for data transmission within a broadband communication system that allows for faster data transmission and more efficient use of supplemental channels than conventional methods.

FIELD OF THE INVENTION The present invention relates generally to cellular communication systems and, in particular, to data transmission within broad-band cellular communication systems.

1 is a block diagram illustrating a base station for transmitting data in accordance with a preferred embodiment of the present invention.

FIG. 2 is a block diagram illustrating the fundamental channel circuitry of FIG. 1 in accordance with a preferred embodiment of the present invention. FIG.

3 is a block diagram illustrating the supplemental channel circuitry of FIG. 1 for transmitting data in accordance with a preferred embodiment of the present invention.

4 and 5 are flow charts illustrating data transmission from the base station of FIG. 1 in accordance with a preferred embodiment of the present invention.

6 and 7 are flow charts illustrating data transmission from the base station of FIG. 1 in accordance with another embodiment of the present invention.

In order to overcome the problems described above, when data transmission is interrupted, the remote unit drops the supplemental channel before responding to the reception of the last frame transmitted, and the response and retransmission are performed using the slow basic channel. If an interruption occurs during the transmission of the supplemental channel, if data to be transmitted below a predetermined size remains, data transmission is continued using the base channel. When responding after interruption of data transmission, the supplemental channel is freed faster and can be used by other data users because the remote unit drops the supplemental channel before performing any response or retransmission. In addition, by using the base channel, error control is performed without noticeable delay. In the case of a timeout (or interruption) when using the supplemental channel, re-access of the supplemental channel for small data transfers is continued since the data continues to be transmitted to the base channel when there is a small amount of data to be transmitted. This does not slow down the transmission of remaining data. Moreover, the supplemental channel is freed more quickly and is used by other data users.

The present invention encompasses a method for data transmission in a broadband communication system. The method includes transmitting data using a second channel and a second encoding scheme, and receiving an interruption during transmission of the data. The transmission of data is stopped and continues with the first coding scheme in the first channel.

The present invention also encompasses other methods for data transmission in broadband communication systems. The method includes transmitting data using a second channel and a second coding scheme, and determining when a plurality of data have been transmitted. When a plurality of data is transmitted and a response is received that a plurality of data have been received, data transmission using the second channel and the second coding scheme is stopped.

The invention also encompasses another method for data transmission in a broadband communication system. The method includes determining if data transmission needs to be made using the second channel and determining if the second channel is available. If the second channel is not available, data is transmitted using the first channel and the first coding scheme, and if the second channel is available, data is transmitted using the second channel and the second coding scheme.

Finally, the present invention encompasses an apparatus for data transmission in a broadband communication system. The apparatus includes a supplemental channel circuit for outputting data in a second coding scheme on a fast second channel, and a controller for outputting an instruction to stop data transmission in the second coding scheme on the second channel; And a basic channel circuit for outputting the data on the first channel in a first encoding manner when the data output on the high speed second channel is stopped.

1 is a block diagram illustrating a base station 100 for transmitting data to a remote unit 113 in accordance with a preferred embodiment of the present invention. Base station 100 is comprised of a controller 101, a plurality of basic channel circuits 103, one or more supplemental channel circuits 105, a summer 111, and a modulator 115. As shown, the base station 100 communicates via the downlink communication signal 117 to the remote unit 113, and the remote unit 113 via the uplink communication signal 119 to the base station 100. Communicate

In a preferred embodiment of the present invention, communication to / from remote unit 113 may take place using supplemental channel circuitry 105 and / or base channel circuitry 103. In particular, base station 100 and remote unit 113 use two classes of channels that are defined for both forward and reverse transmissions. In the description of the preferred embodiment herein, data transmission takes place from the base station 100 to the remote unit 113, but a person of ordinary skill in the art does not depart from the spirit and scope of the present invention. It can be readily appreciated that data transfer can occur in a similar manner from the remote unit 113 to the base station 100 without the communication.

In a preferred embodiment, the base channel is similar to existing CDMA traffic channels and is used for voice, data and signaling except for spread over a wider bandwidth. The CDMA traffic channel is a mobile station base station compatible standard for dual-mode wideband spread spectrum cellular systems, the Telecommunications Industry Association Intern Standard 95A, Washington, DC, July 1993 (Mobile Station-Base Station Compatibility Standards, incorporated herein by reference). for Dual-Mode Wideband Spread Spectrum Cellular Systems, Telecommunication Industry Association Interium Standard 95A, Washington, DC July 1993) "(IS-95A). As described in IS-95A, the transmission rate of the channel may change dynamically. In addition, soft handoff (simultaneous transmission using one or more basic channel circuits 103) is supported using the basic channel circuits 103.

In contrast, the supplemental channel is used to communicate to the remote unit 113 with a high speed data service, where the data rates of the supplemental channels are negotiated prior to transmission. Multiple data sources are multiplexed with time on the channel. Furthermore, the quality of service (QOS) of the channel (eg, Frame Error Rate (FER), Bit Error Rate (BER), and / or Transmission Delay) is set independently of the base channel. Can be operated.

Data transmission from the base station 100 according to the preferred embodiment of the present invention occurs as follows. During times when the remote unit 113 is not actively communicating with the base station 100 using the base channel or supplemental channel, the remote unit 113 is in a suspended state and any impending transmission by the base station 100 is performed. Actively or periodically monitor the forward control channel [IS-95A Paging Channel] for notification of transmission. In particular, a paging channel circuit (not shown) is used to send a message to the remote unit 113 indicating an impending pending downlink transmission. In a preferred embodiment of the invention, the paging channel circuit is a circuit as described in IS-95A sections 7.1.3.4, 7.6.2 and section 7.7.2. Base station 100 determines whether high-speed data transfer needs to occur to remote unit 113 and determines whether supplemental channel circuitry 105 is available. Because the number of supplemental channels available for communication is limited, the supplemental channels may not be available for transmission to the remote unit 113. For this reason, the remote unit 113 is placed in a queue until the supplemental channel circuit 105 is available for transmission. Whether the remote unit 113 is in the queue or not, the remote unit 113 is placed in a "control hold" state assigned to the base channel. In particular, the base station 100 informs the remote unit 113 of the spreading codes (Walsh codes) used by the base and supplemental channels and the assigned data rates of the supplemental channels. In addition, initial power control as described in sections 6.1.2 and 6.6.3.1.1.1 of IS-95A takes place at this point using the base channel.

When the power level is appropriate and the supplemental channel becomes available, the remote unit 113 becomes active, in which communication using the supplemental channel (ie, data transfer) takes place. In particular, the supplemental channel circuitry 105 assigned to the remote unit 113 outputs data to be transmitted to the summer 111, where it is summed with other channel transmissions. These summed transmissions are QPSK modulated by the modulator 115 and transmitted to the remote unit 113 via the downlink communication signal 117.

Transmission on the supplemental channel can be stopped, especially for two reasons. First, all data is communicated to the remote unit 113. In this case, the remote unit 113 performs a response of the last frame transmitted. In particular, error control is performed by acknowledging (ACK) the received packet and / or providing a negative acknowledgment (NAK) when a message with the sequence number is not received even after a numbered message is received. do. (If the NAK procedure is used, even if the protocol uses the NAK only for the course of the rest of the data transfer, the successful reception of the last packet must be answered).

The second reason for stopping transmission on the supplemental channel is that the transmission using the supplemental channel exceeds the allocated time (or simply interrupts). In this case, the data remains to be transmitted to the remote unit 113, and the remote unit 113 is again in a control hold state waiting for continued data transmission.

In the first case mentioned above (when all data is sent to the remote unit 113), the remote unit 113 drops the supplemental channel before responding to the reception of the last frame transmitted, and the acknowledgment is the default. This is done using the channel. In the second case described above (when a time-out or interruption has occurred), if there is still less data to transmit than a predetermined amount, data transmission continues using the base channel. In particular, the controller 101 determines the remaining size of data to send to the remote unit 113, and if there is less data than the predetermined size that needs to be sent to the remote unit, the transmission continues on the base channel. Otherwise, transmission of data continues on the supplemental channel when the supplemental channel becomes available again.

In the case of a response after transmission is interrupted, the supplemental channel is freed more quickly and becomes available to other data users because the remote unit 113 drops the supplemental channel before performing any error control. In addition, error control can be performed without any noticeable delay by using the base channel. In the case of a timeout (or interruption) using the supplemental channel, the remote unit 113 will continue to transmit data on the primary channel if there is little data left to send, so the remote unit 113 will return to the supplemental channel to send a small amount of data. There is no problem of slowing down the transmission of remaining data by access. In addition, the supplemental channel is freed more quickly and becomes available to other data users.

2 is a block diagram illustrating the basic channel circuit of FIG. 1 in accordance with a preferred embodiment of the present invention. The basic channel circuit 103 is composed of a channel multiplexer 201, a convolutional encoder 212, a symbol repeater 215, a block interleaver 216, a long code scrambler 217, and an orthogonal encoder 220. In operation, signal 210 (traffic channel data bits) is received by channel multiplexer 201 at a particular bit rate (e.g., 8.6 kbit / second). The input traffic channel data 210 bits typically include voice, pure data, or a combination of both forms of data converted into data by a vocoder. Channel multiplexer 201 multiplexes second traffic (e.g., data) and / or signaling traffic (e.g., control or user messages) on traffic channel data 210, and multiplexes the multiplexed data at 9.6 kbit /. Output to convolutional encoder 212 in sec. The convolutional encoder 212 uses a encoding algorithm (e.g., convolutional or block coding algorithm) to enable subsequent sub likeequal maximum likelihood decoding from data symbols to data bits. Encodes the input data bits 210 into data symbols. For example, the convolutional encoder 212 may have a fixed encoding rate (i.e. 1/3 rate), with the input data bits 210 (received at a rate of 9.6 kbit / sec) and one data bit as two data symbols. And convolutional encoder 212 outputs data symbol 214 at a rate of 28.8 ksymbol / sec.

Data symbol 214 is repeated by repeater 215 and input to interleaver 216. Interleaver 216 interleaves input data symbol 214 at the symbol level. In interleaver 216, data symbols 214 are individually input into a matrix that defines a predetermined size block of data symbols 214. Data symbols 214 are entered at locations in the matrix, and the matrix is filled in a column by column manner. Data symbols 214 are output separately from places in the matrix so that the matrix is emptied in a row by row manner. In general, a matrix is a square matrix with the same number of rows and columns. However, other matrix forms can also be used to increase the output interleaving distance between input data symbols that are not consecutively interleaved. Interleaved data symbol 218 is output by interleaver 216 at the same rate as the data symbol rate at which the data symbol was input (ie, 28.8 ksymbol / sec). From the maximum number of data symbols that can be transmitted at a predetermined symbol rate within a transmission block of a predetermined length, a predetermined size of the block of data symbols defined by the matrix is obtained. For example, if the predetermined length of a transport block is 20 milliseconds, then the predetermined size of the block of data symbols is 28.8 ksymbol / sec multiplied by 20 milliseconds, which defines an 18 X 32 matrix. do.

The interleaved data symbols 218 are scrambled by a scrambler 217 and output to the orthogonal encoder 220. Quadrature encoder 220 modulo 2 adds an orthogonal code (eg, 256-ary Walsh code) to each interleaved and scrambled data symbol 218. For example, in 256-ary orthogonal encoding, interleaved and scrambled data symbols 218 each perform an 256 OR orthogonal code and an exclusive OR operation. In a preferred embodiment, these 256 orthogonal codes correspond to Walsh codes from a 256 X 256 Hadamard matrix, which Walsh codes are a single row or column of the matrix. Quadrature encoder 220 repeatedly outputs a Walsh code corresponding to input data symbol 218 at a fixed symbol rate (eg, 28.8 ksymbol / second).

The sequence of Walsh codes 242 is further spread by a pair of short (i.e. short when compared to long codes) pseudorandom codes 224, so that I-channel and Q-channel ( Generate a Q-channel code spread sequence 226. I and Q channel code spreading sequences 226 are used to bi-phase modulate quadrature pairs of sinusoids by controlling power levels of sinusoids pairs. . Sinusoids output signals are summed, QPSK modulated (by modulator 115), and radiated by antenna 120 to complete transmission of channel data bits 210. In a preferred embodiment of the present invention, spreading sequence 226 is output at a rate of 3.6864 Mega Chips per second (Mcps) and radiates within a 5 MHz bandwidth. However, in other embodiments of the present invention, the spreading sequence 226 may be output at different speeds and radiated within different bandwidths. For example, an IS-95A transmission scheme may be used in another embodiment of the present invention, where the spreading sequence 226 is output at 1.2288 Mcps (traffic channel chip rate) within a 1.25 MHz bandwidth. Since each data symbol is exclusive ORed by a 128 symbol orthogonal code, the actual input data symbol transmission rate (at step 218) is 19.2 Kcps (using a 1/2 convolutional encoder).

3 is a block diagram illustrating supplemental channel circuitry 105 for transferring data in accordance with a preferred embodiment of the present invention. The supplemental channel circuit 105 includes a channel multiplexer 301, a convolutional encoder 312, a symbol repeater 315, a block interleaver 316, and a quadrature encoder 320. In operation, signal 310 (data) is received by channel multiplexer 301 at a particular bit rate (eg, 152.4 kbit / sec). The channel multiplexer 301 multiplexes the second traffic (eg, user data) onto the supplemental channel data and outputs the multiplexed data to the convolutional encoder 312 at 153.6 kb / s.

Convolutional encoder 312 uses input encoding bits (e.g., rounded or block coding algorithms) to enable subsequent maximum likelihood decoding from data symbols to data bits, at a fixed encoding rate. ) Into a data symbol. For example, the convolutional encoder 312 may have a fixed encoding rate (i.e. 1/3 rate), with the input data bits 310 (received at a rate of 153.6 kbit / sec) and one data bit being two data symbols. And the convolutional encoder 312 outputs data symbols 314 at a rate of 460.8 kbit / sec.

The data symbol 314 is then input to the interleaver 316. Interleaver 316 interleaves input data symbols 314 at the symbol level. In interleaver 316, data symbols 314 are individually input to a matrix that defines a predetermined size block of data symbols 314. Data symbols 314 are entered at locations in the matrix so that the matrix is filled column by column. The data symbols 314 are output separately from places in the matrix so that the matrix is emptied row by row. In general, a matrix is a square matrix with the same number of rows and columns. However, other matrix forms can also be used to increase the output interleaving distance between input data symbols that are not consecutively interleaved. Interleaved data symbol 318 is output by interleaver 316 at the same rate as the data symbol rate at which the data symbols were input (ie, 28.8 ksymbol / sec). From the maximum number of data symbols that can be transmitted at a predetermined symbol rate within a transmission block of a predetermined length, a predetermined size of the block of data symbols defined by the matrix is obtained. For example, if the predetermined length of the transport block is 20 milliseconds, then the predetermined size of the block of data symbols is 9.216 ksymbols.

Interleaved data symbols 318 are repeated by repeater 315 and output to quadrature encoder 320. Quadrature encoder 320 modulo 2 adds an orthogonal code (eg, 16-ary Walsh code) to each interleaved and scrambled data symbol 318. For example, in 16-ary orthogonal encoding, interleaved and scrambled data symbols 318 each perform an 16-OR orthogonal code and an exclusive OR operation. In a preferred embodiment, these 16 orthogonal codes correspond to Walsh codes from a 16 × 16 Hadamard matrix, where the Walsh codes are a single row or column of the matrix. Quadrature encoder 320 repeatedly outputs the Walsh code corresponding to the input data symbol 318 or vice versa at a fixed symbol rate (eg, 460.8 ksymbol / second).

The sequence of weighted Walsh codes 342 is further spread by a pair of short (i.e. short when compared to long codes) pseudo random codes 324 to generate an I channel and a Q channel code spreading sequence 326. . The I-channel and Q-channel code spreading sequence 326 is used for two-phase modulation of the quadrature pairs of the sinusoidal curves by controlling the power levels of the sinusoidal pairs. The sinusoidal output signal is summed, QPSK modulated (by modulator 115), and radiated by antenna 120 to complete transmission of channel data bits 310. In a preferred embodiment of the present invention, spreading sequence 326 is output at a rate of 3.6864 Mega Chips per second (Mcps) and radiates within a 5 MHz bandwidth.

4 and 5 are flow charts illustrating data transmission from the base station of FIG. 1 in accordance with a preferred embodiment of the present invention. In a preferred embodiment of the present invention, data transmission from base station 100 to remote unit 113 is performed using a second (supplemental) channel. However, unlike the conventional data transmission method, the supplemental channel is dropped before all data is successfully transmitted through the supplemental channel. In particular, in a preferred embodiment of the present invention, the response and retransmission of data is performed using the base channel. Moreover, if a timeout or interruption occurs during data transfer, the supplemental channel is dropped and the data transfer proceeds on the base channel.

The logic flow begins at step 401, where the remote unit 113 is in a suspended state and is not in active communication with the base station 100 using the primary or supplemental channel, but rather to the base station 100. Actively monitor the forward control channel (IS-95A paging channel) for notification of any impending transmission. As described above, a paging channel circuit (not shown) is used to send a message to the remote unit 113 indicating an impending downlink transmission. In step 403 the controller 101 determines if a high speed data transfer needs to occur to the remote unit 113. If at step 403 the controller 101 determines that a high speed data transfer does not need to occur, the logic flow returns to step 403, otherwise the logic flow proceeds to step 405. At step 405 the controller 101 determines whether the supplemental channel circuit 105 is available, and if not available the logic flow proceeds to step 407. If not already completed in step 407, the base station 100 notifies the remote unit 113 of the impending data transfer (via the paging channel), assigns the remote unit 113 a first channel (base channel) and The power controls the remote unit 113. The logic flow then returns to step 405. If, at step 405, the controller 101 determines that the supplemental channel circuit 105 is available, the logic flow proceeds to step 409. In step 409, if not completed, the base station 100 notifies the remote unit 113 of the impending data transmission (via the paging channel), assigns the first unit (base channel) to the remote unit 113, and , The power controls the remote unit 113.

In step 415, data transfer using a second channel (supplement channel) takes place. In particular, a first transmission within a first bandwidth (5 MHz) using a second orthogonal coding scheme (second-ary or 16-ary encoding scheme in a preferred embodiment of the present invention). Data transfer begins by sending at the rate (3.6864 Mcps). In step 417, the controller 101 determines if the last frame (packet) of data has been sent to the remote unit 113, and if so, the logic flow continues to step 421. Otherwise, the logic flow continues to step 419, where the controller 101 determines if a timeout or interruption occurs that would cease data transfer. In step 421, transmission on the supplemental channel is stopped (ie, the channel is dropped). In step 423 a response from the remote unit 113 is received from the last frame transmitted (multiple data transmitted) indicating which retransmission of data needs to be performed. In a preferred embodiment of the invention, the response is performed by sending a response by the remote unit 113 to the base station 100 using the base channel. The logic flow continues to step 425, in which the controller 101 determines if data needs to be retransmitted to the remote unit 113, and if so, the logic flow continues to step 427. Otherwise, the logic flow ends at step 429. In step 427 the controller 101 transmits the data to the remote unit 113 via the base channel (ie, the first orthogonal coding scheme (first-ary) or 256 in the preferred embodiment of the present invention. Transmission at a first transmission rate (3.6864 Mcps) within a first bandwidth (5 MHz) using a 256-ary encoding scheme. The logic flow then ends at step 429.

Returning to step 419, if the controller 101 determines that a "timeout" has occurred, the logic flow continues with step 431, and the remaining data to be transmitted to the remote unit 113 in step 431. Determine the size of. Otherwise, the logic flow returns to step 415. Next, at step 433, the controller 101 determines whether the size of the remaining data to be transmitted is greater than a predetermined threshold (eg, 5 frames), and if so, the logic flow proceeds to step 405. If not, the logic flow proceeds to step 427.

As described above, by completing the transfer of data on the base channel, the supplemental channel is freed faster and becomes available to other data users. Moreover, using the base channel allows error control to be performed without noticeable delay.

6 and 7 are flow charts illustrating data transmission from the base station of FIG. 1 in accordance with another embodiment of the present invention. In another embodiment of the present invention, data transfer occurs whenever the supplemental channel circuitry 105 is usable or whenever data needs to be transmitted to the remote unit 113. More specifically, a determination is made as to whether a second channel (supplemental channel) is available, and if the supplemental channel is not available, data is sent using the first channel (base channel), otherwise the data is supplementary. Is sent using the channel.

The logic flow begins at step 501, where the remote unit 113 is in a suspended state and is not in active communication with the base station 100 using the base channel or supplemental channel, but rather to the base station 100. Actively monitor the forward control channel (IS-95A paging channel) for notification of any impending transmission. As described above, a paging channel circuit (not shown) is used to send a message to the remote unit 113 indicating an impending downlink transmission. In step 503 the controller 101 determines if a high speed data transfer needs to occur to the remote unit 113. If at step 503 the controller 101 determines that a high speed data transfer does not need to occur, the logic flow returns to step 503, otherwise the logic flow proceeds to step 505. At step 505 the controller 101 determines whether the supplemental channel circuit 105 is available and if not available the logic flow continues to step 507. In step 407, if not completed, the base station 100 notifies the remote unit 113 of the impending data transmission (via the paging channel), assigns the first unit (base channel) to the remote unit 113, and The power controls the remote unit 113. Next, in step 508, within a first bandwidth (5 MHz) using a first orthogonal coding scheme (first-ary or 256-ary coding scheme in a preferred embodiment of the present invention). The data transmission occurs by transmitting at the first transmission rate (3.6864 Mcps). The logic flow then returns to step 505. If the controller 101 determines that the supplemental channel circuitry 105 is available at step 505, the logic flow proceeds to step 509. In step 509, if not completed, the base station 100 notifies the remote unit 113 of the impending data transmission (via the paging channel), assigns the remote unit 113 a first channel (base channel) and , The power controls the remote unit 113.

In step 515 data transfer using a second channel (supplement channel) takes place. In particular, a first transmission rate (within a first bandwidth (5 MHz) using a second orthogonal coding scheme (second-ary or 16-ary coding scheme in a preferred embodiment of the present invention) is obtained. 3.6864 Mcps) to start the data transfer. At step 517, the controller 101 determines if the last frame (packet) of data has been sent to the remote unit 113, and if so, the logic flow continues to step 521. However, otherwise the logic flow continues to step 519 where controller 101 determines if a timeout or interruption occurs. In step 521, the transmission on the supplemental channel is stopped (ie, the channel is dropped). In step 523 a response of the last frame transmitted is received from the remote unit 113, indicating which retransmission of data needs to be performed. In a preferred embodiment of the invention, the response is performed by sending a response by the remote unit 113 to the base station 100 using the base channel. The logic flow continues to step 525, in which the controller 101 determines if data needs to be retransmitted to the remote unit 113, and if so, the logic flow continues to step 527. Otherwise, the logic flow ends at step 529. In step 527 the controller 101 transmits the data to the remote unit 113 via the base channel (ie, first orthogonal coding scheme (first-ary) or 256 in the preferred embodiment of the present invention. (256-ary) coding scheme) at a first transmission rate (3.6864 Mcps) within a first bandwidth (5 MHz). The logic flow then ends at step 529.

Returning to step 519, if the controller 101 determines that a "timeout" has occurred, the logic flow continues with step 531, where in step 531 the transmission on the supplemental channel is stopped and the logic flow stops. Return to 508. In step 508, data transmission continues over the base channel. If at step 519 the controller 101 determines that a "timeout" has not occurred, the logic flow returns to step 515. Since data transfer occurs on the base channel whenever the supplemental channel is not available, the size of the data to be transmitted to the remote unit 113 is increased as compared to the conventional method of transferring data.

While the invention has been described herein in connection with specific embodiments, it will be apparent to those skilled in the art that various changes may be made in form or detail without departing from the spirit and scope of the invention. It is to be understood that the changes are within the scope of the following claims.

Claims (9)

A method for data transmission in a broadband communication system, Transmitting data using a second channel and a second encoding scheme; Receiving an interruption during transmission of the data using the second channel and the second coding scheme; Stopping transmission of the data using the second channel and the second encoding scheme; And Continuing transmission of the data using a first channel and a first encoding scheme Data transmission method comprising a. The method of claim 1, Determining a residual amount of data to transmit after receiving the interruption; And If the remaining amount of data to be transmitted is below a threshold, continuing to transmit the data using the first channel and the first encoding scheme. Data transmission method further comprising. The method of claim 1, wherein transmitting data using the second channel and the second encoding scheme comprises transmitting data using the second channel and a second-ary encoding scheme. Data transmission method. The method of claim 3, wherein the continuing of the data transmission using the first channel and the first encoding scheme comprises transmitting data using the first channel and a first-ary encoding scheme. A data transfer method comprising the steps. The method of claim 1, Determining when the second channel becomes available after receiving the interruption; And Continuing transmission of the data using the second channel and the second coding scheme when the second channel becomes available. Data transmission method further comprising. The method of claim 1, wherein transmitting the data using the first channel and transmitting the data using the second channel are respectively performed. Transmitting the data using a slow data channel; And Transmitting said data using a high speed data channel. An apparatus for data transmission in a broadband communication system, Supplemental channel circuitry for outputting data on a fast second channel in a second coding scheme; A controller for outputting an indication to stop data transmission in the second encoding scheme on the second channel; And Fundamental channel circuitry for outputting the data in a first coding scheme on a first channel when the data output on the fast second channel is stopped. Data transmission device comprising a. 8. The apparatus of claim 7, wherein the supplemental channel circuit transmits data using a second-ary encoding scheme. 10. The apparatus of claim 8, wherein the basic channel circuit transmits data using a first-ary encoding scheme.